[HELP]Updating gamma in modded wii

Hi everyone here is my situation
I have a modded wii which have v3.2u, HBC , Gamma 0.3(Without 002 fix)
I want to change it to neo gamma as i have alot problem with games like virtual tennis 2k9 and wii sports resort etc
So im asking if that
1) my only solution is to format it and re upgrade?
2) or update it with a SD card with correct files?
Any one mind provide a good help for me as im stuck with this for months
and oh ya.. i want to do a nand backup
so can i do another nand backup when my HBC is already installed?
* Things to note *
My wii is already modded when i bought it so i dun even have any single experience on modding it
i have my SD card ready for any replies

I have read through the forums like ULTIAMTE system menu 4.0 or [Guide] Fully softmod any wii But to no avail.
Anyone mind provide me a very good tutorial to aid on my upgrading HBC and Backuploader to a newer version
Or any really related reference will do
Thanks in advance!
Please do help out!!! xD

Well, you can't update to neogamma, because they're made by different people. If you want neogamma, simply download the .wad file for it (get it here)
If you dont already have wad manager, go find it, download it and put into your apps folder. Then, take the wad file that you just downloaded and put it into the wad folder on the root of SD. Now simply open homebrew channel, run wad manager and install the neogamma wad. Finally, you'll probably want to uninstall gamma loader, so if you still have the wad file, put it in the wad folder, go to wad manager and uninstall it.

And yes you can do a NAND backup no problem.

By the way, do you know if you have a modchip installed? Because most of the time, premodded wiis have them, and they're much more convenient than just softmodded wiis.